Problem: Simplify the following expression: $n = \dfrac{2x + 9}{4x + 1} \div \dfrac{1}{10}$
Answer: Dividing by a number is the same as multiplying by its inverse. $n = \dfrac{2x + 9}{4x + 1} \times \dfrac{10}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $n = \dfrac{(2x + 9) \times 10} {(4x + 1) \times 1}$ $n = \dfrac{20x + 90}{4x + 1}$